1. Industrial Application
This application relates to a load transport lifter having a moveable base frame with a lift table coupled to a cylinder mechanism and vertical struts; the lift table can be raised or lowered by cables coiled around sprockets on the end of the cylinder mechanism.
2. Description of Related Art
The related art includes the apparatus described in Japanese Publication No. 130597 (1988), which consists of a fork-shaped lift platform supported horizontally by parallel scissor links disposed on top of a moveable base frame. One end of a pair of chains is fixed to the moveable base frame, while the other end is wrapped around sprockets at the end of piston rods in a cylinder set disposed vertically with respect to the moveable base frame and connected to the base of the lift platform. The lift platform moves up or down along with the piston rods and the action of the chains.
Other work platforms are disclosed in Japanese Publications No. 70657 (1974) and No. 202598 (1988). These have a self-leveling load platform mounted horizontally on a movable base frame; the load platform, through springs and electrical or mechanical means, adjusts its position to the amount of load and automatically maintains an optimum height for unloading and loading activities.
The objective of the first type of lifter disclosed above is mainly as a transport apparatus to transport loads loaded onto a pallet, or loads loaded directly onto the lifter platform. This being the case, little consideration is given to unloading of loads when the lifter is in a fixed position, thus leaving the adjustment of the height of the pallet or lifter platform solely to the discretion of the operator.
Conversely, the objective of the second type of load platform is to improve the process of unloading loads, therefore making the apparatus unsuited for transporting loads. Depending on the condition of the floor, the load may become unstable; in addition, if the load should fall from the load platform, the resilience of the springs would make the platform suddenly move upwards, making stability and safety difficult to maintain. Further, when using a pallet to transport loads, if the amount of the load were to exceed the resilience of the springs, the pallet would come into contact with the floor and the lifter would become unable to move. Finally, since the highest height reachable by the lifter platform is limited, almost no reduction in the effort required for loading and unloading from high places can be expected.
Therefore, due to the differences of purpose and function of the prior-art lifters and load platforms, it is impossible to conduct a series of operations with a lifter involving both transporting and loading/unloading and also using a lifter as a work platform. At present these functions are performed separately according to the kind of work involved.